Storage Apparatus and Method for Executing Exclusive Extent Processing in Parallel Using Counter Values

1. A storage apparatus which is connected via a network to a host apparatus that issues data input/output (I/O) requests, comprising: a microprocessor package configured to access a logical volume to which the microprocessor package has ownership rights, wherein: the microprocessor package includes a plurality of microprocessors and any of the plurality of microprocessors can access the logical volume; and the logical volume includes one or more storage areas provided by a plurality of storage devices; a local memory in the microprocessor package, the local memory configured to: store a counter value indicating a number of I/O requests to and from a logical volume; and lock the local memory when a counter value is to be incremented; wherein each microprocessor in the microprocessor package is configured to: store, if there is one I/O request from the host apparatus, an I/O request range of the one I/O request in the local memory, wherein the I/O request range includes a start position address and an end position address of the logical volume which is a target of the I/O request; acquire the counter value of the logical volume which is the target of the one I/O request; store the acquired counter value in the local memory; if the counter value of the logical volume associated with the one I/O request is greater than the counter value of the logical volume associated with another I/O request, compare the I/O request range of the one I/O request stored in the local memory and the I/O request range of the other I/O request; if, as a result of comparing the I/O request range of the one I/O request stored in the local memory and the I/O request range of the other I/O request, there is no overlap between the I/O request ranges, execute the one I/O request processing; and if there is an overlap between the I/O request ranges, place the processing of the one I/O request on standby.

2. The storage apparatus according to claim 1 , wherein after storing the acquired counter value in the local memory, each microprocessor is further configured to add ‘1’ to the acquired counter value and store the sum in the local memory.

3. The storage apparatus according to claim 1 , wherein the local memory is further configured to store control information of I/O requests, wherein the control information includes the counter value, the I/O request range, information indicating whether the counter value and the I/O request range are valid values, and information indicating whether I/O processing can be executed.

4. The storage apparatus according to claim 3 , wherein each microprocessor is further configured to compare the I/O request range of the one I/O request and the I/O request range of the other I/O request if the counter value and the I/O request range included in the control information of the other I/O request are valid.

5. The storage apparatus according to claim 3 , wherein if the one I/O request processing is executed, each microprocessor is further configured to store information indicating that I/O processing can be executed in the control information of the one I/O request, and if the processing of the one I/O request is placed on standby, each microprocessor is further configured to store information indicating that the execution of the I/O processing has been placed on standby in the control information of the one I/O request.

6. The storage apparatus according to claim 1 , wherein, if an I/O queue of the I/O request linked to each of the storage areas is searched starting with a most recently used (MRU) storage area and moving toward a least recently used (LRU) storage area and the counter value of a specific I/O request is greater than the counter value of an I/O request corresponding to a searched for I/O queue, each microprocessor is further configured to compare the I/O request range of the specific I/O request stored in the local memory and an I/O request range of the searched for I/O request.

7. The storage apparatus according to claim 6 , wherein each microprocessor is further configured to create a search list which indicates a search order for searching for I/O queues in the storage areas which are the access targets of the one I/O request before searching, from the MRU toward the LRU, for the I/O queues of each of the storage areas and comparing the I/O request range of the one I/O request.

8. The storage apparatus according to claim 7 , wherein each microprocessor is further configured to add identification information, which identifies a plurality of I/O queues of each of the storage areas, to the search list.

9. A data access method which employs a storage apparatus connected via a network to a host apparatus that issues data input/output (I/O) requests, the storage apparatus including: a microprocessor package configured to access a logical volume to which the microprocessor package has ownership rights, wherein the microprocessor package includes a plurality of microprocessors and any of the plurality of microprocessors can access the logical volume, and the logical volume includes one or more storage areas provided by a plurality of storage devices; and a local memory in the microprocessor package, the local memory configured to store a counter value indicating a number of I/O requests to and from a logical volume, and lock the local memory when a counter value is to be incremented; the data access method comprising: storing, if there is one I/O request from the host apparatus, an I/O request range of the one I/O request in the local memory by one of the microprocessors, wherein the I/O request range includes a start position address and an end position address of the logical volume which is a target of the I/O request; acquiring the counter value of the logical volume which is the target of the one I/O request; storing the acquired counter value in the local memory by the one microprocessor; if the counter value of the logical volume associated with the one I/O request is greater than the counter value of the logical volume associated with another I/O request, the one microprocessor comparing the I/O request range of the one I/O request stored in the local memory and the I/O request range of the other I/O request; if, as a result of comparing the I/O request range of the one I/O request stored in the local memory and the I/O request range of the other I/O request, there is no overlap between the I/O request ranges, the one microprocessor executing the one I/O request processing; and if there is an overlap between the I/O request ranges, the one microprocessor placing the processing of the one I/O request on standby.